| department of population ecology | ::: | institute | ::: | university | ::: |  |
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dr hab. Mariusz Cichoń
cichon@eko.uj.edu.pl |
Dep. of Population Ecology Inst. of Environmental Sciences Jagiellonian University Gronostajowa 7, 30-387 Kraków Poland tel. + 48 12 664 52 01 fax + 48 12 664 69 12 |
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Dubiec A., Cichoń M.
CAN J ZOOL
2001; 79: 1829-1833
Abstract:
Seasonal variation in offspring survival and recruitment rate in birds may be mediated by immune function as it defines the ability of individuals to protect themselves against parasites and infectious diseases. To investigate the relation between hatching date and health status of great tit nestlings, two blood parameters (leukocyte level and haematocrit) were estimated. Leukocyte level decreased with the progress of the season within first, but not second broods, while haematocrit showed no seasonal variation within either brood type. However, nestlings from first broods had higher levels of both leukocytes and haematocrit than nestlings from second broods. Nestling condition (defined as residuals of body mass on tarsus length calculated from linear regression) was not related to hatching date within brood type, while a significant difference was found between brood types. We suggest that the commonly observed decline in juvenile survival with the progress of the season may be at least partly attributed to seasonal changes in health status.
d e s i g n e d b y P a w e ł K a p u s t a